Gonna have to vote no on the tail, even Jak doesn't run it anymore:
I wouldn't say the torsion bars will hinder your handling, seemed to work pretty well on the 911. Here's a good link to get you started:
http://www.aircooled.net/gnrlsite/re...s/handling.htm
Let's see here, removing the runningboards looks weird unless you do something about the body area that it exposes. It might be easier (and cheaper) to buy a disc brake conversion kit in a porsche lug pattern, just the single piston ones still stop pretty hard. As far as I know, 944 trailing arms are just lighter, and won't really do anything else for you.
Your purpose for the car seems to kinda be all over the place, did you want to build the car for motorsports? You might consider reading the rules and restrictions on modifications for the class you'd like to run in.
For the engine, it all depends on your budget. You can build either style to perform for your needs, but if you're going all-new, the type 1 will probably be easier on your wallet.